Campbell was born on April 4, 1833, in Jefferson County, Ohio, the son of Archibald W. Campbell and Phoebe Campbell. His father was a physician and a younger brother of Alexander Campbell, the religious reformer and member of the Convention of 1829–1830. Campbell grew up in or near Bethany, in Brooke County, where his uncle had founded Bethany College and his father practiced medicine. He graduated from Bethany College in 1852 and studied law at Hamilton College Law School in New York, where he met William H. Seward. Within a few years Campbell followed Seward into the new Republican Party and, like him, became an abolitionist.
Campbell returned to Virginia and settled in Wheeling. In the autumn of 1856 he and John F. McDermot purchased the Wheeling Daily Intelligencer. On October 9 of that year Campbell became the editor. During the next two years he used the Intelligencer to express his antislavery views. It became not only the first Republican daily newspaper in Virginia but also perhaps the best known and most influential Virginia newspaper outside Richmond. Campbell unsuccessfully proposed in 1859 that the second national convention of the Republican Party meet the following year in Wheeling. It met, instead, in Chicago, where he was a delegate supporting Seward for president. Afterward Campbell warmly endorsed the nomination of Abraham Lincoln, who received about 800 votes in Ohio County in the November election.
Campbell believed that the proslavery policies of Virginia’s state government were injurious to northwestern Virginia, but he did not initially expect that Lincoln’s election would result in Virginia’s secession or that the western counties would in turn separate from Virginia. His attitude quickly changed when the Convention of 1861 adopted the Ordinance of Secession. Thereafter Campbell used the Wheeling Daily Intelligencer to argue that the interests of western Virginia and of democracy required the establishment of a new state. He was one of the most influential leaders in the statehood movement and strongly supported the abolition of slavery by the first West Virginia constitution.
Campbell remained a loyal Republican during and after the Civil War, but he occasionally differed with national party leaders when he believed that the interests of the party ran contrary to those of West Virginia. He dissented on withholding suffrage from former supporters of the Confederacy, on refusing to make an alliance with the Greenback Party, and on a proposed third presidential term for Ulysses S. Grant in 1880. So strong was Campbell’s opposition to party leaders in 1880 that some considered expelling him from the national convention. He forcefully argued his case at the convention, retained his seat, and also received some credit for the eventual nomination for president of his friend James A. Garfield. Although frequently urged to seek public office, Campbell rejected suggestions that he run for the U.S. Senate or jockey for a position in Garfield’s cabinet.
In Wheeling on March 10, 1864, Campbell married Annie W. Crawford. They had one son and one daughter. Sometime after her death he married a second time to a woman named Mary H., surname unknown, with whom he had at least one daughter. During the 1880s he gradually relinquished his role as editor and publisher of the Intelligencer in order to pursue other business interests. Campbell died following a stroke at his sister’s home in Webster Groves, Missouri, on February 13, 1899. He was buried in Greenwood Cemetery in Wheeling, West Virginia.